Wow... new user impressed

Hey everyone, I just received my Vibrant in the mail today (having high expectations for it), and it still managed to impress me. Side by side with my old phone (iPhone 2G), the screen looked amazing to say the least. When a video has a black border around it, I literally can't tell where the screen starts. Also, the multi-tasking is very nice, I love the phone already!

Just a couple questions, though. Should I switch to a different ROM, or leave the stock one Samsung and T-Mobile put on my phone? Also, please leave me any tips for must-have applications and widgets, there's no such thing as too many applications if they're all useful in some way! So yeah, just any tips you can give a new Android user would be very much appreciated.